Nowadays, automotive vehicles comprise several electronic modules for controlling the diverse sensors and/or actuators situated on the vehicle. Certain modules manage the sensors and/or the actuators of the power train. They are called ECU (“Engine Control Unit”). Others manage the sensors and/or actuators situated in the bodywork of the vehicle, they are called BCM (“Body Control Module”), that is to say control module relating to the sensors and/or actuators situated in the bodywork of the vehicle. The BCM thus manages in particular the approach and/or contact detection sensors situated in the doors' handles of the vehicle.
These approach and/or contact detection sensors are capacitive sensors, known to the person skilled in the art, that detect the approach and/or the contact of a user's hand on a locking or unlocking zone of the handle. The capacitive sensor detects this approach and/or contact, and then it dispatches a detection information item to the BCM. The BCM receives this information item, as well as other information items originating from other sensors and/or actuators of the vehicle, for example the information item relating to the state of the door (locked/unlocked), or the information item relating to the identifier of the device for hands free access to the vehicle, that is to say of the key or of the badge carried by the user. The microcontroller of the BCM then analyses all these data in order to verify that the user is properly authorized to access the vehicle and that a locking or unlocking can be carried out. If the user is authorized, the BCM then triggers the locking or the unlocking of the vehicle, that is to say it operates the actuators for locking or unlocking the door.
The dimensions of the vehicle door handle being quite small, the latter generally contains only the detection sensor, that is to say at least one detection electrode, a microcontroller and associated electronics (electrical supply for example), and sometimes an emission antenna. Detection is carried out by the microcontroller integrated into the sensor, but the control of the locking or unlocking of the door is centralized in the BCM, on receipt of the approach and/or contact detection information item dispatched by the microcontroller integrated into the sensor and as may or may not be the case, as explained previously, on receipt of other information items originating from the vehicle.
There is therefore a unidirectional communication between the detection sensor and the BCM, since the sole function of the sensor is to inform the BCM when an approach has been detected. In FIG. 1 is represented the electronic diagram of the communication between a detection sensor 20 and a BCM 10. The BCM 10, comprises a microcontroller 11, connected to a voltage of the battery VBAT by a current-supply line W1, and connected to the ground GND. The BCM 10 also comprises a resistor R1, situated on the supply line W1. The microcontroller 11 of the BCM 10 and associated electronics (not represented) make it possible to measure a voltage across the terminals of the resistor R1.
The detection sensor 20 comprises an electrical supply 21 connected directly to the voltage of the battery VBAT, by the supply line W1, and connected to the ground GND by the BCM 10. The detection sensor 20 furthermore comprises, a microcontroller 22, connected to an approach and/or contact detection electrode 23. The microcontroller 22 of the detection sensor 20 monitors the variation of the capacitance between the electrode 23 and the ground GND. When this capacitance exceeds a threshold, thereby signifying the approach and/or the contact of a hand of the user on the handle, the microcontroller 22 then dispatches an approach and/or contact detection signal to the BCM 10. Accordingly, the microcontroller 22 closes a first switch S1. This closure creates an inrush of current through a resistor R10 placed between the switch S1 and the supply line W1, downstream of the resistor R1. This current inrush propagates toward the BCM 10 and is then detected by the microcontroller 11 of the BCM 10 and the associated electronics, at the terminals of the resistor R1. By closing according to a determined sequence the switch S1, the microcontroller 22 of the detection sensor 20 thus dispatches an approach and/or contact detection signal to the microcontroller 11 of the BCM 10 by way of the supply line W1. The microcontroller 11 of the BCM 10, after analysis of this detection signal, undertakes the locking or unlocking.
This device is known to the person skilled in the art.
However, the latest trend is to add functionalities in the door handle of a vehicle, in particular to add a light source which will turn on according to one or more precise event(s) detected by the BCM 10. This light source, generally a light-emitting diode, commonly dubbed LED, is integrated into the detection sensor 20 and connected to the microcontroller 22.
This is carried out with the aim of user comfort or with the aim of esthetics. This light source is turned on for example when a certain darkness around the vehicle has been detected, and when a user authorized to access the vehicle has been detected in proximity to the vehicle. The turning on of the light source can also be triggered after the user gets out of his vehicle and the doors are closed so as to light up the locking zone or the unlocking zone situated inside the handle on which he must press to lock his door. Or else, this light source is turned on when the user has touched the handle, in order to light up the unlocking zone on which the user must press to unlock the openable panels of his vehicle and get into his vehicle. These events (presence of an authorized user around the vehicle, getting out of the user, closing of the door, detection of contact on the handle, etc.), originating from the various sensors/actuators of the vehicle, are detected by the BCM 10.
Now, on the supply line W1, the current inrushes generated to turn on the light source are of the same order of magnitude as the current inrushes generated during the communication between the detection sensor 20 and the BCM 10. When the light source is turned on, communication from the sensor to the BCM 10 is therefore impossible.
The existing solutions propose to control the turning on of the light source by the addition of an extra wire link-up between the BCM 10 and the detection sensor 20.
Now, the addition of a wire link-up between the BCM 10 and the detection sensor 20 situated in the door handle goes with problems regarding integration, because of the restricted space in the handle, problems regarding connection arrangements and cost for the BCM 10, since the latter must be specifically modified for the types of handles comprising an LED, and consequently a generic BCM common to all the types of handles is no longer conceivable.